a heavy steel transverse bar in the form of an inverted U rising from the framework of an automobile to prevent its occupants from being crushed if the vehicle rolls over.
Origin of roll bar
First recorded in 1950–55
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for rollbar
/ (ˈrəʊlˌbɑː) /
a bar that reinforces the frame of a car, esp one used for racing, rallying, etc, to protect the driver if the car should turn over
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012